In radio communication systems, such as WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), and LTE-A (LTE-Advanced) which are proposed by 3GPP (Third Generation Partnership Project), and WiMAX (Worldwide Interoperability for Microwave Access) proposed by IEEE (The Institute of Electrical and Electronics Engineers), a communication area can be enlarged by providing a cellular configuration including a plurality of base station devices (each also called eNB or eNodeB) deployed such that ranges (cells) in each of which the base station device is connectable with a mobile station device (also called a terminal or UE (User Equipment)) are set to be partly overlapped with each other.
In order to increase the frequency usage efficiency of the cells in the above-described cellular configuration, it is studied, as discussed in Non Patent Literature (NPL) 1 mentioned below, (i) to repeatedly utilize the same frequency by the individual cells, or (ii) to construct a heterogeneous network in which, in addition to a base station device (macrocell) having a cell radius of several hundred meters to over ten kilometers, other base station devices (each called a picocell, a femtocell, or Home eNodeB) having various cell radii are deployed such that ranges of the other base station devices entirely or partly overlap with the macrocell.
FIG. 22 is a schematic view illustrating one example of a downlink in a radio communication system in which base station devices having different cell radii are deployed. A base station device 1000-2 is deployed with Single Frequency Reuse such that a cell 1000-2a (e.g., a picocell) of the base station device 1000-2 overlaps with a cell 1000-1a (macrocell) of a base station device 1000-1. A mobile station device is preferably controlled to be radio-connected to the base station device capable of receiving a signal with higher strength of a received electric field. In FIG. 22, a mobile station device 2000-1 is radio-connected (as denoted by r11) to the base station device 1000-1, and mobile station devices 2000-2 and 2000-3 are radio-connected to the base station device 1000-2 (as denoted by r21 and r23). Furthermore, when the picocell is deployed so as to include a cell edge and thereabout of the macrocell (i.e., in a region where the strength of the electric field is weak), the power of a signal received by the mobile station device can be increased by connecting the mobile station device 2000-3, which is present at the cell edge of the macro cell, to the picocell.
Thus, by constructing the heterogeneous network as described above, the frequency usage efficiency can be increased in total when viewed from networks present within an area covered by the macrocell.